1. Field of the Invention
The present invention relates to a diagnosis apparatus using XCT (X-ray computed tomography) and, more particularly, to a diagnosis apparatus for diagnosing a function of blood vessels by XCT.
2. Description of the Related Art
A demand has arisen for diagnosing a function of blood vessels, in particular, a function of blood vessels in a brain. The blood vessels in a brain has a function called blood brain barriers, and prevent plasm in blood from directly permeating into the brain. However, the blood brain barrier may not function for some reasons, and plasm in the blood may directly permeate in the brain. In order to diagnose such a state, an apparatus for diagnosing a blood brain barrier (BBB) has been developed. Such an apparatus is disclosed in "Simplified, Noninvasive PEP Measurement of Blood-Barrier Permeability", "J comput Assist Tomogr, Vol. 11, No. 3, 1987", pp. 390-397. According to the apparatus in this paper, a radioactive material such as (68G) EDTA is used as a contrast medium, and a subject to which this contrast medium has been injected is scanned by a PET (Position Emission Tomography) device. Parameters associated with a function of a blood brain barrier are calculated in accordance with PET (positron emission tomography) data obtained by this scanning operation, and the parameters are monitored as functional images, and are used for diagnosis.
In the above-mentioned conventional apparatus, a radioactive material is used as a contrast medium. The life of the radioactive material is short and, at most, about several hours. For this reason, the radioactive material serving as a contrast medium must be manufactured immediately before diagnosis. Therefore, an equipment (hot-labo) for manufacturing the contrast medium must be arranged in a diagnosis section. The PET device is used as a scanner to obtain PET data. However, this PET is a very expensive equipment, and has a problem that its space resolution is relatively low, i.e., 3 mm to 10 mm, and a noise is large.